Fig. 1

Cell proliferation in the adult zebrafish olfactory epithelium. (A) Schematic overview of the zebrafish OE, which forms by repeated folding of the epithelial sheet to give rise to double-faced radial lamellae. The sensory epithelium of neighbouring lamellae is continuous at the interlamellar curves (ILCs) and joined at the basal lamina. Olfactory sensory neurons are restricted to the inner region (blue) sharply separated from respiratory cells in the peripheral nonsensory OE (red) at the sensory/nonsensory border (SNS). The radial index (top, right) depicts the scale for morphometric measurements of cell positions normalized to the length between the tip of ILCs and the position of the SNS. (B) Immunohistochemistry against the mitotic marker phospho-histone H3 (PH3, red, left) and the pan-neuronal marker HuC/D (green, centre) on full sections through the adult zebrafish OE (top) and higher power view of one side of the OE (bottom) indicated by the grey box. Mitotically active cells (arrowheads) occur at the ILCs (asterisks) and SNS (dotted line). The solid line depicts the outline of the section. Scale bars: 100 µm. (C) Immunohistochemistry against BrdU (blue, left) after 24 h BrdU incubation to label dividing cells and HuC/D (green, centre) to visualize mature neurons on full sections (top) and higher power views of one side of the OE (bottom) indicated by the grey box. BrdU-positive cells are restricted to the ILCs (asterisks) and SNS (dotted line) but are completely absent from the center of the sensory OE. BrdU/HuC/D double-positive cells occur at the edge of the sensory OE (arrowheads). Scale bars: 100 µm.